Subject: ADRC-176A
Dear Jay,
We are currently curating the abstracts for the upcoming Bellevue
(Seattle) Annual Drosophila Research Conference, for FlyBase. I am
writing in connection with your abstract:
'Identification and genetic characterization of Su(dpp)39CDE, a
dominant maternal effect suppressor of decapentaplegic.'
You mention a gene that is new to FlyBase, Su(dpp)39CDE. Do you have
an allele symbol for the EMS allele e.g. Su(dpp)39CDE1?
You mention a map location for Su(dpp)39CDE, but do not say how that
location was determined. Would it be possible for you to give us a
little more so that the mapping info can be stored more robustly in
FlyBase? It looks like it was probably delimited by deficiency breaks,
or similar. Could you tell us which aberrations were used?
Thank you for your help,
with best wishes,
Rachel.
Subject: Re: ADRC-176A
Hello Rachel,
The genetics here are atypical. The mutant, Su(dpp)39CDE, is actually
a dominant maternal effect suppressor of the dpp haploinsufficiency
phenotype, but it turns out that homozygotes are perfectly viable and
fertile on their own.
The mapping data arises from the following peculiar observation:
homozygous Su mothers will enhance 3X and 4X dpp copy number. That is,
flies bearing 3 or 4 wildtype copies of dpp will die with greater
frequency compared to their 2X sibs when their mother is Su homozygous.
Astonishingly, and most relevant to the mapping discussion, Su/Df also
gives the same enhancement result, even though Df/+ neither suppresses
haploinsufficiency nor enhances >2X dpp.
Therefore, the Su is probably a gain of function mutation, and Su/Df
mothers behave as Su/Su mothers, at least with regard to enhancement of
>2X dpp. My speculation is that the presence of a wildtype copy of this
gene ameliorates the effects of the mutant on >2X dpp, hence the
observation that Su/+ mothers do not enhance.
The Df's over which the enhancement effect is observed are:
TW161
TW84
TW65
The enhancement effect is NOT observed over:
TW1
TW12
...hence the estimated cytological position.
As for an allele symbol, Su(dpp)39CDE1 makes sense to me.
Best Regards,
Jay.